btrfs-progs: convert: Fix inline file extent creation condition

btrfs-progs: convert: Fix inline file extent creation condition

[Bug]
On btrfs converted from ext*, one user reported the following kernel
warning:
 ------------[ cut here ]------------
 BTRFS: Transaction aborted (error -95)
 WARNING: CPU: 0 PID: 324 at fs/btrfs/inode.c:3042 btrfs_finish_ordered_io+0x7ab/0x850 [btrfs]
 Workqueue: btrfs-endio-write btrfs_endio_write_helper [btrfs]
 RIP: 0010:btrfs_finish_ordered_io+0x7ab/0x850 [btrfs]
 ...
 Call Trace:
  normal_work_helper+0x39/0x370 [btrfs]
  process_one_work+0x1ce/0x410
  worker_thread+0x2b/0x3d0
  ? process_one_work+0x410/0x410
  kthread+0x113/0x130
  ? kthread_create_on_node+0x70/0x70
  ? do_syscall_64+0x74/0x190
  ? SyS_exit_group+0x10/0x10
  ret_from_fork+0x35/0x40
 ---[ end trace c8ed62ff6a525901 ]---
 BTRFS: error (device dm-2) in
btrfs_finish_ordered_io:3042: errno=-95 unknown
 BTRFS info (device dm-2): forced readonly
 BTRFS error (device dm-2): pending csums is 6447104

[Cause]
The call trace and the unique return value points to
__btrfs_drop_extents(), when we tries to drop pages of an inline extent,
we will trigger such -EOPNOTSUPP.

However kernel has limitation on the size of inline file extent
(sector size for ram size and sector size - 1 for on-disk size),
btrfs-convert doesn't have the same limitation, resulting much larger
file extent.

The lack of correct inline extent size check dates back to 2008 when
btrfs-convert is added into btrfs-progs.

[Fix]
Fix the inline extent creation condition, not only using
BTRFS_MAX_INLINE_DATA_SIZE(), which is only the maximum size of inline
data according to nodesize, but also limit it against sector size.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>